The Houston Veterans Affairs Medical Center is currently performing LVRS under a protocol supported by Merit Review funding (1996-200O, Effects of lung volume reduction surgery in the treatment of severe emphysema) in selected patients with severe emphysema. This controlled study is designed to determine patient selection criteria, as well as, both the short and long term benefits of operated and non-operated patients with severe emphysema receiving maximal medical therapy. Given the strict selection criteria and unexpectedly high survival in both treatment groups to date, it is unlikely in a study of this size that survival differences will be detected.